Trilobite ID

[Kane]

A bit uncertain about this one. I spent a few hours this morning on the "mountain" today, which has a lot of fill from the Bois Blanc Fm. This pygidium showed up. Although it was my first instinct, I'm not satisfied with declaring this an Eldredgeops rana. Despite their occurrence in that formation, I find most E. rana pygidia to be much more shorter/truncated. Comparing against Ludvigsen's photographs, I am not satisfied with the diagnostic details in terms of similarity here (maybe more like Dechenella?). And the ribbing on this tail seems a bit more detailed than E. rana. I might also rule out Anchiopsis due to a lack of the pygidial spike (although it is not clear on this specimen if there might have been one as there is no clear termination at the bottom). I've looked at a number of my E. rana for comparison, and they lack the pygidial detail that this one has.

 

I apologize in advance if this one is a no-brainer and a waste of other folks' expertise.

 

Width at widest point = 1.8 cm.

 

The specimen on the lower right (positive and negative) looks to be E. rana, although the librigena seems a bit small (which may mean it is buried in the matrix, but I'll have to use some tools to determine that).

[Pumpkinhead]

Perhaps it is the pygidium of a species of Dalmanites with the terminal spine broken off

[Kane]

Just now, Pumpkinhead said:

Perhaps it is the pygidium of a species of Dalmanites with the terminal spine broken off

I'm getting a bit of the dalmanitid vibe, too. If so, it may be the case I have another example of Anchiopsis anchiops. That would be good news for me, although it is frustrating to never find a full one!

[piranha]

It is another Anchiopsis anchiops.  The medially incised axial ring furrows are a dalmanitid feature.

 

[Kane]

Thank you, @piranha... I'm sorry I'm not pulling something a bit less common (and nothing exciting) from these rocks  (but now I'll know to be on the lookout for that feature on the axial rings).